Sunday, May 24, 2015

The packaging of malware and malware-construction kits for cybercrime
“consumers” has been a long-running trend. Various turnkey kits that
cover remote access plus botnet plus stealth functions are available
just about anywhere. Ransomware, though very prevalent, has not yet
appeared in force in easy-to-deploy kits.But now we have Tox–and it’s free.

While sifting though our stream of “dark web” data, McAfee Labs found
Tox on May 19. It was updated on May 21 with a new FAQ and an updated
design. But the core did not change.

Salient Points:

Tox is free. You just have to register on the site.

Tox is dependent on TOR and Bitcoin. That allows for some degree of anonymity.

The malware works as advertised.

Out of the gate, the standard of antimalware evasion is fairly high,
meaning the malware’s targets would need additional controls in place
(HIPS, whitelisting, sandboxing) to catch or prevent this.

Once you register for the product, you can create your malware in three simple steps.

Enter the ransom amount. (The site takes 20% of the ransom.)

Enter your “cause.”

Submit the captcha.

This process creates an executable of about 2MB that is disguised as a
.scr file. Then the Tox “customers” distribute and install as they see
fit. The Tox site (on the TOR network) will track the installs and
profit. To withdraw funds, you need only supply a receiving Bitcoin
address.

Upon execution, the malware encrypts the victims’ data and prompts them
for the ransom, including the Bitcoin address for sending payment.

Technical InformationAlthough easy to use and functional, the malware appears to lack complexity and efficiency within the code.

Tox malware portable executable sections.

The developer has left several identifying strings within the code. Examples:

C:/Users/Swogo/Desktop/work/tox/cryptopp/secblock.h

C:/Users/Swogo/Desktop/work/tox/cryptopp/filters.h

C:/Users/Swogo/Desktop/work/tox/cryptopp/cryptlib.h

C:/Users/Swogo/Desktop/work/tox/cryptopp/simple.h

Tox-generated malware is compiled in MinGW and uses AES to encrypt
client files via the Crypto++ library. The Microsoft CryptoAPI is used
for key generation.Network InformationThe malware first downloads Curl and the TOR client:

hxxp://www.paehl.com/open_source/?download=curl_742_1.zip

hxxp://dist.torproject.org/torbrowser/4.5.1/tor-win32-0.2.6.7.zip

All downloaded files and artifacts are stored in the following path:

C:\Users\<username>\AppData\Roaming\

After execution, Tox will start TOR in SOCKS5 proxy mode with the following command-line parameters: